A molecular assessment of phylogenetic relationships and lineage accumulation rates within the family Salamandridae (Amphibia, Caudata)

A new species of the newt genus Hypselotriton (Amphibia, Urodela, Salamandridae) from Jiangxi Province, southeastern China

A new newt species, Hypselotritonhuanggangensis sp. nov., is described based on nine specimens collected from Huanggangshan Mountains, Yanshan County, Jiangxi, China. Morphologically, the new species is characterized by the combination of nine external characters: (1) obvious black patches with clear boundaries on the whole body; (2) ground color of the dorsal body tan; (3) ground color of venter bright orange; (4) skin rough; (5) vertebral ridge weak; (6) fingers and toes overlapping when forelimb and hindlimb adpressed towards each other along body; (7) postocular orange spot absent; (8) small white warty glands around the eye; (9) two discontinuous longitudinal lines formed by white warty glands from neck to lateral parts of tail. Molecularly, the new species forms an independent clade with strong support in the phylogenetic trees of the genus based on the mitochondrial locus of NADH dehydrogenase subunit 2 (ND2) gene fragments. The new species distinctly differs from H.fudingensis by differences in its body measurements, vertebral ridge, dorsal black patches, and ventral black patches. Furthermore, the new species and H.fudingensis are geographically isolated by a series of high mountain ranges, including the Wuyishan and Jiufengshan Mountains. The number of Hypselotriton species is now 11.

Demographic and ecological niche dynamics of the Vietnam warty newt, Paramesotriton deloustali: Historical climate influences

Quaternary climatic cycles strongly affected the genetic diversification and ranges of organisms, shaping current genetic structures and distribution patterns. Urodeles provide ideal examples for exploring these dynamics over time and across space. In this study, we integrated a phylogeographic approach and ensemble species distribution modeling (eSDM) to infer the historical demography and distribution patterns of the Vietnam warty newt, Paramesotriton deloustali. Mitochondrial data revealed two groups, West and East, which diverged approximately 1.92 million years ago (Mya). Diversification was likely driven by change in the climate during early stages of the Pleistocene, with increasing monsoon and drought intensities. Biogeographic analysis indicated that the newt's current distribution formed as a result of vicariance events. In addition, the two groups occupy distinct ecological niches. Demographic reconstruction showed signs of expansion in the effective population sizes of the two major groups beginning around 0.11 and 0.15 Mya, respectively. However, eSDM showed fluctuating predicted distributions during the last interglacial, last glacial maximum, mid-Holocene, and present. Mountain systems in northern Vietnam are likely to have served as climatic refuges and to have played a crucial role in safeguarding species from the effects of climate change.

A synoptic review of the Amphibians of Iran: bibliography, taxonomy, synonymy, distribution, conservation status, and identification key to the eggs, larvae, and adults

This study provides an illustrated account, a comprehensive update of the systematics, and a bibliography of the 15 species of anurans in five families, eight genera; and of the six species of urodeles in two families, four genera in Iran. Bufonidae, with eight species, is the most diverse family; Salamandridae has five species and Ranidae has four species. This study also presents updated identification keys for the eggs, larvae, and metamorphosed amphibians of Iran. We designated specimen NMW 19855.1 as neotype of Pelophylax persicus (Schneider, 1799) comb. nov.. Along with distribution maps obtained from all the reliable localities and museum specimens known at this time, the modelled habitat of species, and for the first time, the National Red List of amphibians based on the IUCN red list categories and criteria. Based on our evaluation we propose to categorize Bufo eichwaldi, Paradactylodon persicus, Neurergus derjugini, and N. kaiseri as Vulnerable at National Red List, and to move Bufotes (Calliopersa) luristanicus, B. (C.) surdus, Firouzophrynus olivaceus, and Rana pseudodalmatina from the category of Least Concern (LC) to Near Threatened (NT). The National Red List of amphibians that we propose has significant implications for endangered species management and conservation. Forty-one percent of amphibian species in Iran are endemic to the country, and more than forty percent of the Iranian amphibians are at risk of extinction. Zagros Mountain forest and Hyrcaniain forests have more than 80% (i.e. 18 species) of the diversity of Iranian amphibians. A considerable amount of scientific literature published on Iranian amphibians in Persian language is not easily accessible to researchers outside Iran. This monograph attempts to remedy the situation and provides broader access to international herpetology. We recognize that taxonomy is always in a state of flux, and the names and synonymies used here reflect our current view.

Characterization, Comparison of Two New Mitogenomes of Crocodile Newts Tylototriton (Caudata: Salamandridae), and Phylogenetic Implications

Mitochondrial genomes (mitogenomes) are valuable resources in molecular and evolutionary studies, such as phylogeny and population genetics. The complete mitogenomes of two crocodile newts, Tylototriton broadoridgus and Tylototriton gaowangjienensis, were sequenced, assembled, and annotated for the first time using next-generation sequencing. The complete mitogenomes of T. broadoridgus and T. gaowangjienensis were 16,265 bp and 16,259 bp in lengths, which both composed of 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and 1 control region. The two mitogenomes had high A + T content with positive AT-skew and negative GC-skew patterns. The ratio of non-synonymous and synonymous substitutions showed that, relatively, the ATP8 gene evolved the fastest and COI evolved the slowest among the 13 PCGs. Phylogenetic trees from BI and ML analyses resulted in identical topologies, where the Tylototriton split into two groups corresponding to two subgenera. Both T. broadoridgus and T. gaowangjienensis sequenced here belonged to the subgenus Yaotriton, and these two species shared a tentative sister group relationship. The two mitogenomes reported in this study provided valuable data for future molecular and evolutionary studies of the genus Tylotoriton and other salamanders.

A new species of the genus Tylototriton (Urodela, Salamandridae) from western Thailand

We describe a new species of the newt genus Tylototriton from Umphang Wildlife Sanctuary, Tak Province, western Thailand based on molecular and morphological evidence and named here as Tylototritonumphangensissp. nov. The new species is assigned to the subgenus Tylototriton and differs from other species in having dark-brown to blackish-brown body and limbs, truncate snout, prominent antero-medial ends of the expansion of the dentary bones, laterally protruding quadrate regions, indistinct and small rib nodules, a well-segmented vertebral ridge, and rough dorsolateral bony ridges, which are steeper anterior, and curved medially at the posterior ends. The molecular data show that Tylototritonumphangensissp. nov. differs from T.uyenoi sensu stricto by a 5% genetic sequence divergence of the mitochondrial NADH dehydrogenase subunit 2 region gene. The new species and T.uyenoi are both endemic to Thailand, distributed along the Northwest Thai (Dawna) Uplands of Indochina. To clarify the species boundary between Tylototritonumphangensissp. nov. and T.uyenoi, additional field research is needed in adjacent areas. Tylototritonumphangensissp. nov. is restricted to evergreen hill forests in Umphang Wildlife Sanctuary. We suggest that the new species should be classified as Endangered (EN) in the IUCN Red List.

Newt regeneration genes regulate Wingless signaling to restore patterning in Drosophila eye

Newts utilize their unique genes to restore missing parts by strategic regulation of conserved signaling pathways. Lack of genetic tools poses challenges to determine the function of such genes. Therefore, we used the Drosophila eye model to demonstrate the potential of 5 unique newt (Notophthalmus viridescens) gene(s), viropana1-viropana5 (vna1-vna5), which were ectopically expressed in L 2 mutant and GMR-hid, GMR-GAL4 eye. L 2 exhibits the loss of ventral half of early eye and head involution defective (hid) triggers cell-death during later eye development. Surprisingly, newt genes significantly restore missing photoreceptor cells both in L 2 and GMR>hid background by upregulating cell-proliferation and blocking cell-death, regulating evolutionarily conserved Wingless (Wg)/Wnt signaling pathway and exhibit non-cell-autonomous rescues. Further, Wg/Wnt signaling acts downstream of newt genes. Our data highlights that unique newt proteins can regulate conserved pathways to trigger a robust restoration of missing photoreceptor cells in Drosophila eye model with weak restoration capability.

Karyological Diversification in the Genus Lyciasalamandra (Urodela: Salamandridae)

Simple Summary

The Lycian salamanders of the genus Lyciasalamandra are characterized by a debated taxonomy and phylogenetic relationships. They have been the subject of various molecular and phylogenetic analyses, but their chromosomal diversity is completely unknown. We here present a comparative cytogenetic analysis on five out of the seven described species and seven subspecies of Lyciasalamandra, providing the first karyological assessment on the genus and comparing them to closely related representatives of the genus Salamandra. We analyzed the occurrence and distribution of different conserved (chromosome number and morphology) and highly variable karyological features. We found an impressive diversity in the configuration of nucleolus organizing regions (NORs), which alternatively occur either as heteromorphic or homomorphic loci on distinct regions of different chromosome pairs. We highlight that the observed peculiar taxon-specific pattern of chromosome markers supports the taxonomic validity of the different studied evolutionary lineages and is consistent with a scenario of synchronous evolution in the Lycian salamanders.

Abstract

We performed the first cytogenetic analysis on five out of the seven species of the genus Lyciasalamandra, including seven subspecies, and representatives of its sister genus Salamandra. All the studied species have a similar karyotype of 2n = 24, mostly composed of biarmed elements. C-bands were observed on all chromosomes, at centromeric, telomeric and interstitial position. We found a peculiar taxon-specific NOR configuration, including either heteromorphic and homomorphic NORs on distinct regions of different chromosomes. Lyciasalamandra a.antalyana and L. helverseni showed two homomorphic NORs (pairs 8 and 2, respectively), while heteromorphic NORs were found in L. billae (pairs 6, 12), L. flavimembris (pairs 2, 12), L. l. luschani (pairs 2, 12), L. l. basoglui (pairs 6, 12), L. l. finikensis (pairs 2, 6) and S. lanzai (pairs 8, 10). Homomorphic NORs with an additional supernumerary site were shown by S. s. salamandra (pairs 2, 8) and S. s. gigliolii (pairs 2, 10). This unexpected highly variable NOR configuration is probably derived from multiple independent NOR translocations and paracentric inversions and correlated to lineage divergence in Lyciasalamandra. These results support the taxonomic validity of the studied taxa and are consistent with a hypothesized scenario of synchronous evolution in the genus.

Historic range dynamics in Kaiser's mountain newt (Neurergus kaiseri): Insights from phylogeographic analyses and species distribution modeling

Vulnerable Kaiser's mountain newt, Neurergus kaiseri, is endemic to highland streams, springs, and pools of the southwestern Zagros mountain, Iran. The present study aimed to use an integration of phylogeographical and species distribution modeling (SDM) approaches to provide new insights into the evolutionary history of the species throughout Quaternary climate oscillations. The phylogeographical analysis was followed by analyzing two mitochondrial DNA (mt-DNA) markers including 127 control region (D-loop) and 72 NADH dehydrogenase 2 (ND2) sequences from 15 populations in the entire species range that were obtained from GenBank. Potential recent and past distribution (the Last Glacial Maximum, LGM, 21 Kya and the Mid-Holocene, 6 Kya) reconstructed by ensemble SDM using nine algorithms with CCSM4, MIROC-ESM, and MPI-ESM-P models. N. kaiseri displayed two distinct lineages in the northern and southern regions that diverged in the Early-Pleistocene. The demographics analysis showed signs of a slight increase in effective population size for both northern and southern populations in the Mid-Pleistocene. Biogeography analysis showed that both vicariance and dispersal events played an important role in the formation of recent species distribution of N. kaiseri. Based on SDM projection onto paleoclimatic data, N. kaiseri displayed a scenario of past range expansion that followed by postglacial contraction. The models showed that the distribution range of the species may have shifted to a lower altitude during LGM while with amelioration of climatic during Mid-Holocene to recent conditions caused the species to shift to the higher altitude. The findings of the current study support the hypothesis that the Zagros mountains​ may be acting as climatic refugia and play an important role in the protection of isolated populations during climate oscillations.

Phylotranscriptomic evidence for pervasive ancient hybridization among Old World salamanders

Hybridization can leave genealogical signatures in an organism's genome, originating from the parental lineages and persisting over time. This potentially confounds phylogenetic inference methods that aim to represent evolution as a strictly bifurcating tree. We apply a phylotranscriptomic approach to study the evolutionary history of, and test for inter-lineage introgression in the Salamandridae, a Holarctic salamanders group of interest in studies of toxicity and aposematism, courtship behavior, and molecular evolution. Although the relationships between the 21 currently recognized salamandrid genera have been the subject of numerous molecular phylogenetic studies, some branches have remained controversial and sometimes affected by discordances between mitochondrial vs. nuclear trees. To resolve the phylogeny of this family, and understand the source of mito-nuclear discordance, we generated new transcriptomic (RNAseq) data for 20 salamandrids and used these along with published data, including 28 mitochondrial genomes, to obtain a comprehensive nuclear and mitochondrial perspective on salamandrid evolution. Our final phylotranscriptomic data set included 5455 gene alignments for 40 species representing 17 of the 21 salamandrid genera. Using concatenation and species-tree phylogenetic methods, we find (1) Salamandrina sister to the clade of the "True Salamanders" (consisting of Chioglossa, Mertensiella, Lyciasalamandra, and Salamandra), (2) Ichthyosaura sister to the Near Eastern genera Neurergus and Ommatotriton, (3) Triturus sister to Lissotriton, and (4) Cynops paraphyletic with respect to Paramesotriton and Pachytriton. Combining introgression tests and phylogenetic networks, we find evidence for introgression among taxa within the clades of "Modern Asian Newts" and "Modern European Newts". However, we could not unambiguously identify the number, position, and direction of introgressive events. Combining evidence from nuclear gene analysis with the observed mito-nuclear phylogenetic discordances, we hypothesize a scenario with hybridization and mitochondrial capture among ancestral lineages of (1) Lissotriton into Ichthyosaura and (2) Triturus into Calotriton, plus introgression of nuclear genes from Triturus into Lissotriton. Furthermore, both mitochondrial capture and nuclear introgression may have occurred among lineages assigned to Cynops. More comprehensive genomic data will, in the future, allow testing this against alternative scenarios involving hybridization with other, extinct lineages of newts.

Osteology of the Italian endemic spectacled salamanders, Salamandrina spp. (Amphibia, Urodela, Salamandridae): selected skeletal elements for palaeontological investigations

Salamandrina perspicillata, from Northern and Central Italy, and Salamandrina terdigitata, from Southern Italy, represent a unique case of endemism among the amphibians of Europe. Some efforts were made to study the biology and ecology of these species, but only few studies focused on their comparative osteology. In particular, detailed descriptions of isolated skeletal elements and comparisons with other European urodeles are not available in literature hindering the identification of their fossils that testify for an ancient much broader range. The correct identification of fossil remains, mostly based on careful osteological descriptions, is fundamental to study the evolution of the range of this genus through time and the origin of the current endemic condition. This work is focused on the description of selected skeletal elements (occipito-otic complex, limb bones, atlas, trunk, sacral, caudosacral and caudal vertebrae) of dry-prepared skeletons and CT-scans of wet preserved specimens, which are the most common in the fossil record. We provide osteological comparison of Salamandrina with other genera of Europe, yielding diagnostic characters which allow the identification of fossils at a generic level. No significant differences between the two species S. perspicillata and S. terdigitata were found in the described skeletal elements, thus, the identification of skeletal elements at the species level is, at the moment, impossible.

Integrative taxonomy reveals three new taxa within the Tylototriton asperrimus complex (Caudata, Salamandridae) from Vietnam

The Tylototritonasperrimus complex from northern Vietnam is reviewed based on morphological comparisons and analysis of the mitochondrial marker NADH dehydrogenase subunit 2 (ND2). Based on molecular divergences, which were revealed to be higher than in other congeners, in concert with morphological differences, two new species and one subspecies are described herein: Tylototritonpasmansisp. nov. differs from T.asperrimussensu stricto by 3.2 to 3.6 % genetic divergence and a combination of distinct morphological characters, such as head slightly longer than wide, distinct mid-dorsal ridge, relatively wide distance between the eyes, tips of fingers reaching the eye when foreleg is laid forward, labial and gular folds present, central belly skin with tubercles shaped like transverse wrinkles and distinct, pointy to round rib nodules. The population of T.pasmansisp. nov. consists of two subclades, the nominotypic one occurring on the eastern side of the Da River (or Black River, including Hoa Binh and Phu Tho provinces), and another occurring on the western side (including Son La and Thanh Hoa provinces). These two subclades differ by 2.5 to 3.1 % genetic divergence and distinct morphological characters. The western subclade is herein described as Tylototritonpasmansiobstissp. nov., which differs from the nominotypic form by a wider head, longer and narrower snout, shorter femur length, and an overall less granulose skin, without an increased concentration of warts on the body sides.

A second new species, Tylototritonsparreboomisp. nov. is described from Lai Chau Province. It differs from T.asperrimussensu stricto by 4.1 to 4.2 % and from Tylototritonpasmansisp. nov. by 3.6 to 4.5 % genetic divergences as well as by a combination of distinct morphological characters, such as head longer than wide, tips of fingers reaching nostril when foreleg adpressed along head, rib nodules distinct, round and relatively enlarged, and wide distance between the eyes.

Slow life-history strategies are associated with negligible actuarial senescence in western Palaearctic salamanders

Actuarial senescence has been viewed for a long time as an inevitable and uniform process. However, the work on senescence has mainly focused on endotherms with deterministic growth and low regeneration capacity during the adult stage, leading to a strong taxonomic bias in the study of ageing. Recent studies have highlighted that senescence could indeed display highly variable trajectories that correlate with species life-history traits. Slow life histories and indeterminate growth seem to be associated with weak and late senescence. Furthermore, high regenerative abilities could lead to negligible senescence in ectotherms. However, demographic data for species that would allow testing of these hypotheses are scarce. Here, we investigated senescence patterns in 'true salamanders' from the western Palaearctic. Our results showed that salamanders have slow life histories and that they experience negligible senescence. This pattern was consistent at both intra- and interspecific levels, suggesting that the absence of senescence may be a phylogenetically conserved trait. The regenerative capacities of salamanders, in combination with other physiological and developmental features such as an indeterminate growth and a low metabolic rate, probably explain why these small ectotherms have lifespans similar to that of large endotherms and, in contrast with most amniotes, undergo negligible senescence. Our study seriously challenges the idea that senescence is a ubiquitous phenomenon in the tree of life.

The changing views on the evolutionary relationships of extant Salamandridae (Amphibia: Urodela)

The phylogenetic relationships among members of the family Salamandridae have been repeatedly investigated over the last 90 years, with changing character and taxon sampling. We review the changing composition and the phylogenetic position of salamandrid genera and species groups and add a new phylogeny based exclusively on sequences of nuclear genes. Salamandrina often changed its position depending on the characters used. It was included several times in a clade together with the primitive newts (Echinotriton, Pleurodeles, Tylototriton) due to their seemingly ancestral morphology. The latter were often inferred as a monophyletic clade. Respective monophyly was almost consistently established in all molecular studies for true salamanders (Chioglossa, Lyciasalamandra, Mertensiella, Salamandra), modern Asian newts (Cynops, Laotriton, Pachytriton, Paramesotriton) and modern New World newts (Notophthalmus, Taricha). Reciprocal non-monophyly has been established through molecular studies for the European mountain newts (Calotriton, Euproctus) and the modern European newts (Ichthyosaura, Lissotriton, Neurergus, Ommatotriton, Triturus) since Calotriton was identified as the sister lineage of Triturus. In pre-molecular studies, their respective monophyly had almost always been assumed, mainly because a complex courtship behaviour shared by their respective members. Our nuclear tree is nearly identical to a mito-genomic tree, with all but one node being highly supported. The major difference concerns the position of Calotriton, which is no longer nested within the modern European newts. This has implications for the evolution of courtship behaviour of European newts. Within modern European newts, Ichthyosaura and Lissotriton changed their position compared to the mito-genomic tree. Previous molecular trees based on seemingly large nuclear data sets, but analysed together with mitochondrial data, did not reveal monophyly of modern European newts since taxon sampling and nuclear gene coverage was too poor to obtain conclusive results. We therefore conclude that mitochondrial and nuclear data should be analysed on their own.

Novel erythrocyte clumps revealed by an orphan gene Newtic1 in circulating blood and regenerating limbs of the adult newt

The newt, a group of urodele amphibians, has outstanding ability to repeatedly regenerate various body parts, even in the terrestrial life-stage. In this animal, when the limb is amputated, a cell mass named the blastema appears on the stump and eventually gives rise to a new functional limb. Erythrocytes (red blood cells) in most non-mammalian vertebrates, including the newt, preserve their nucleus throughout their life-span, although physiological roles of such nucleated erythrocytes, other than oxygen delivery, are not known. Here we report novel behavior of erythrocytes in the newt. We identified an orphan gene Newtic1, whose transcripts significantly increased in the blastema. Newtic1 was expressed in a subset of erythrocytes that formed a novel clump (EryC). EryC formed a complex with monocytes and was circulating throughout the body. When the limb was amputated, EryCs were newly generated in the stump and accumulated into a distal portion of the growing blastema. Our data suggested that the newt erythrocytes carried multiple secretory molecules including growth factors and matrix metalloproteases, and were capable of delivering these molecules into the blastema as a form of EryCs. This study provides insight into regulations and roles of nucleated erythrocytes, that are independent of oxygen delivery.

Courtship behaviour and male sexual competition of the Taliang crocodile newt, Liangshantriton taliangensis

The Taliang crocodile newt, Liangshantriton taliangensis, which is endemic to south-western China, is a rare salamandrid species with a distinct evolutionary history. Using combined field observations and captive experiments, we studied the courtship behaviour and male sexual interference of this species and composed a complete ethogram of its courtship behaviour. Unlike previous reports on sperm transfer, male L. taliangensis did not deposit spermatophores during ventral amplexus and females did not pick up sperm masses in this courtship phase. Sperm transfer was only performed during arm-hooking pin-wheel circling, which distinguishes L. taliangensis from Tylototriton species and supports the validity of genus Liangshantriton. Whether L. taliangensis shows bimodality in sperm transfer needs to be explored in additional populations. In the presence of sexual competitors, male L. taliangensis adjusted the duration of their behaviour. We found that males with longer snout-vent length, heavier mass, and higher tailfins may have an advantage in intrasexual competition.

The complete mitochondrial genome of Paramesotriton chinensis (Caudata: Salamandridae) and phylogenetic studies of Paramesotriton

The complete mitochondrial genome of the Asian warty newt Paramesotriton chinensis was sequenced. The complete mitogenome of P. chinensis is a circular double-stranded DNA sequence that is 16,361 bp long and was biased toward A + T content at 61.3% (33.0% A, 28.3% T, 23.9% C, and 14.7% G). The complete mitogenome of P. chinensis consists of 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), 1 ribosomal RNAs (16S rRNA), and 1 putative control region. This study presented the complete mitogenome of P. chinensis and provided essential and important DNA molecular data for further phylogenetic and evolutionary analysis for genus Paramesotriton.

Islands within an island: Population genetic structure of the endemic Sardinian newt, Euproctus platycephalus

The identification of historic and contemporary barriers to dispersal is central to the conservation of endangered amphibians, but may be hindered by their complex life history and elusive nature. The complementary information generated by mitochondrial (mtDNA) and microsatellite markers generates a valuable tool in elucidating population structure and the impact of habitat fragmentation. We applied this approach to the study of an endangered montane newt, Euproctus platycephalus. Endemic to the Mediterranean island of Sardinia, it is threatened by anthropogenic activity, disease, and climate change. We have demonstrated a clear hierarchy of structure across genetically divergent and spatially distinct subpopulations. Divergence between three main mountain regions dominated genetic partitioning with both markers. Mitochondrial phylogeography revealed a deep division dating to ca. 1 million years ago (Mya), isolating the northern region, and further differentiation between the central and southern regions ca. 0.5 Mya, suggesting an association with Pleistocene severe glacial oscillations. Our findings are consistent with a model of southward range expansion during glacial periods, with postglacial range retraction to montane habitat and subsequent genetic isolation. Microsatellite markers revealed further strong population structure, demonstrating significant divergence within the central region, and partial differentiation within the south. The northern population showed reduced genetic diversity. Discordance between mitochondrial and microsatellite markers at this scale indicated a further complexity of population structure, in keeping with male-biased dispersal and female philopatry. Our study underscores the need to elucidate cryptic population structure in the ecology and conservation strategies for endangered island-restricted amphibians, especially in the context of disease and climate change.

Sexual dimorphism and age of Mediterranean salamanders

We analysed sexual size dimorphism (SSD) for two Mediterranean species of the "true" salamander clade possessing distinct life histories (Salamandra algira and Mertensiella caucasica) and equilibrated the morphometric approach to individual age by using skeletochronology. For species that have a short breeding season and live at high altitudes, such as Mediterranean amphibians, the fecundity advantage hypothesis predicts female-biased SSD to maximise reproductive success. Our results showed no SSD in either species; however, morphometric data indicated a male-biased dimorphism in limb (arm and leg) dimensions in both species when compared to body size. Limb dimorphisms are likely related to the particular mating system, which involves an amplexus during spermatophore transfer. Arm length appeared sexually dimorphic during ontogeny both in viviparous S. algira and oviparous M. caucasica. A review on SSD indicated monomorphy of body size as a common lineage-specific pattern among the "true" salamander clade, but also the common presence of other traits such as sexually dimorphic limb proportions.

Flexibility is everything: prey capture throughout the seasonal habitat switches in the smooth newt Lissotriton vulgaris

Transitions between aquatic and terrestrial habitats are significant steps in vertebrate evolution. Due to the different biophysical demands on the whole organism in water and air, such transitions require major changes of many physiological functions, including feeding. Accordingly, the capability to modulate the pre-programmed chain of prey-capture movements might be essential to maintain performance in a new environment. Newts are of special interest in this regard as they show a multiphasic lifestyle where adults change seasonally between an aquatic and a terrestrial stage. For instance, the Alpine newt is capable of using tongue prehension to feed on land only when in the terrestrial stage, but still manages to suction feed if immersed whilst in terrestrial stage. During the aquatic stage, terrestrial feeding always involved grasping prey by the jaws. Here, we show that this seasonal shift in feeding behavior is also present in a species with a shorter terrestrial stage, the smooth newt Lissotriton vulgaris. Behavioral variability increases when animals change from aquatic to terrestrial strikes in the aquatic stage, but prey-capture movements seem to be generally well-coordinated across the feeding modes. Only suction feeding in the terrestrial stage was seldom performed and appeared uncoordinated. Our results indicate that newts exhibit a high degree of seasonal flexibility of the prey-capture behavior. The similarity between movement patterns of suction feeding and terrestrial feeding suggests that only relatively subtle neuromotoric adjustments to the ancestral, suction-feeding motor program are required to successfully feed in the new environment.

Phylogeny and historical demography of Cynops pyrrhogaster (Amphibia: Urodela): taxonomic relationships and distributional changes associated with climatic oscillations

We investigated the phylogenetic relationships and estimated the historical demography of the Japanese fire-bellied newt, Cynops pyrrhogaster, from Japanese mainlands using 1407-bp sequences of the mitochondrial DNA (NADH6, tRNAglu, cyt b) and 1208-bp sequences of nuclear DNA (Rag-1) genes. Phylogenetic trees based on mitochondrial DNA revealed four major haplotype clades (NORTHERN, CENTRAL, WESTERN, and SOUTHERN clades) within this species. Degree of genetic differentiation among major haplotype clades was very large for intraspecific variation, suggesting this species to be composed of four species lineages that replace each other geographically. Nuclear genetic variation presented no obvious patterns of geographic structure except for the distinctness of populations diagnosed by NORTHERN clade of mitochondrial haplotypes, suggesting results of incomplete lineage sorting. Current distribution and estimated divergence times for the genus Cynops suggest that the common ancestor of two Japanese species (C. pyrrhogaster and C. ensicauda from the Ryukyu Islands) had diverged at the edge of the continent corresponding to the present East China Sea and Central Ryukyus. Subsequent range expansion to Japanese mainland seems to have occurred in the middle Miocene. Population-genetic analyses indicated that all species lineages, except for the SOUTHERN one, experienced geographic population reductions and expansions associated with glacial and postglacial climatic oscillations.

Mitochondrial genomes and divergence times of crocodile newts: inter-islands distribution of Echinotriton andersoni and the origin of a unique repetitive sequence found in Tylototriton mt genomes

Crocodile newts, which constitute the genera Echinotriton and Tylototriton, are known as living fossils, and these genera comprise many endangered species. To identify mitochondrial (mt) genes suitable for future population genetic analyses for endangered taxa, we determined the complete nucleotide sequences of the mt genomes of the Japanese crocodile newt Echinotriton andersoni and Himalayan crocodile newt Tylototriton verrucosus. Although the control region (CR) is known as the most variable mtDNA region in many animal taxa, the CRs of crocodile newts are highly conservative. Rather, the genes of NADH dehydrogenase subunits and ATPase subunit 6 were found to have high sequence divergences and to be usable for population genetics studies. To estimate the inter-population divergence ages of E. andersoni endemic to the Ryukyu Islands, we performed molecular dating analysis using whole and partial mt genomic data. The estimated divergence ages of the inter-island individuals are older than the paleogeographic segmentation ages of the islands, suggesting that the lineage splits of E. andersoni populations were not caused by vicariant events. Our phylogenetic analysis with partial mt sequence data also suggests the existence of at least two more undescribed species in the genus Tylototriton. We also found unusual repeat sequences containing the 3' region of cytochrome apoenzyme b gene, whole tRNA-Thr gene, and a noncoding region (the T-P noncoding region characteristic in caudate mtDNAs) from T. verrucosus mtDNA. Similar repeat sequences were found in two other Tylototriton species. The Tylototriton taxa with the repeats become a monophyletic group, indicating a single origin of the repeat sequences. The intra-and inter-specific comparisons of the repeat sequences suggest the occurrences of homologous recombination-based concerted evolution among the repeat sequences.

Phylogeny and biogeography of the Anderson's crocodile newt, Echinotriton andersoni (Amphibia: Caudata), as revealed by mitochondrial DNA sequences

The Anderson's crocodile newt, Echinotriton andersoni, is considered a relic and endangered species distributed in the Central Ryukyus. To elucidate phylogenetic relationships and detailed genetic structures among populations, we analyzed variation in the mitochondrial cytochrome b gene. Results strongly support a primary dichotomy between populations from the Amami and Okinawa Island Groups with substantial genetic divergence, favoring a primary divergence between the two island groups. Within the latter, populations from the southern part of Okinawajima Island are shown to be more closely related to those from Tokashikijima Island than to those from the northern and central parts of Okinawajima. The prominent genetic divergence between the two island groups of the Central Ryukyus seems to have initiated in the Miocene, i.e., prior to formation of the strait that has consistently separated these island groups since the Pleistocene. The ancestor of the southern Okinawajima-Tokashikijima is estimated to have migrated from the northern and central parts of Okinawajima into southern Okinawajima at the Pleistocene, and dispersed into Tokashikijima subsequently.

Understanding of the impact of chemicals on amphibians: a meta-analytic review

Many studies have assessed the impact of different pollutants on amphibians across a variety of experimental venues (laboratory, mesocosm, and enclosure conditions). Past reviews, using vote-counting methods, have described pollution as one of the major threats faced by amphibians. However, vote-counting methods lack strong statistical power, do not permit one to determine the magnitudes of effects, and do not compare responses among predefined groups. To address these challenges, we conducted a meta-analysis of experimental studies that measured the effects of different chemical pollutants (nitrogenous and phosphorous compounds, pesticides, road deicers, heavy metals, and other wastewater contaminants) at environmentally relevant concentrations on amphibian survival, mass, time to hatching, time to metamorphosis, and frequency of abnormalities. The overall effect size of pollutant exposure was a medium decrease in amphibian survival and mass and a large increase in abnormality frequency. This translates to a 14.3% decrease in survival, a 7.5% decrease in mass, and a 535% increase in abnormality frequency across all studies. In contrast, we found no overall effect of pollutants on time to hatching and time to metamorphosis. We also found that effect sizes differed among experimental venues and among types of pollutants, but we only detected weak differences among amphibian families. These results suggest that variation in sensitivity to contaminants is generally independent of phylogeny. Some publication bias (i.e., selective reporting) was detected, but only for mass and the interaction effect size among stressors. We conclude that the overall impact of pollution on amphibians is moderately to largely negative. This implies that pollutants at environmentally relevant concentrations pose an important threat to amphibians and may play a role in their present global decline.

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

Continental islands offer an excellent opportunity to investigate adaptive processes and to time microevolutionary changes that precede macroevolutionary events. We performed a population genetic study of the fire salamander (Salamandra salamandra), a species that displays unique intraspecific diversity of reproductive strategies, to address the microevolutionary processes leading to phenotypic and genetic differentiation of island, coastal and interior populations. We used eight microsatellite markers to estimate genetic diversity, population structure and demographic parameters in viviparous insular populations and ovoviviparous coastal and interior populations. Our results show considerable genetic differentiation (F(ST) range: 0.06-0.27), and no clear signs of gene flow among populations, except between the large and admixed interior populations. We find no support for island colonization by rafting or intentional/accidental anthropogenic introductions, indicating that rising sea levels were responsible for isolation of the island populations approximately 9000 years ago. Our study provides evidence of rapid genetic differentiation between island and coastal populations, and rapid evolution of viviparity driven by climatic selective pressures on island populations, geographic isolation with genetic drift, or a combination of these factors. Studies of these viviparous island populations in early stages of divergence help us better understand the microevolutionary processes involved in rapid phenotypic shifts.

DNA barcoding amphibians and reptiles

Only a few major research programs are currently targeting COI barcoding of amphibians and reptiles (including chelonians and crocodiles), two major groups of tetrapods. Amphibian and reptile species are typically old, strongly divergent, and contain deep conspecific lineages which might lead to problems in species assignment with incomplete reference databases. As far as known, there is no single pair of COI primers that will guarantee a sufficient rate of success across all amphibian and reptile taxa, or within major subclades of amphibians and reptiles, which means that the PCR amplification strategy needs to be adjusted depending on the specific research question. In general, many more amphibian and reptile taxa have been sequenced for 16S rDNA, which for some purposes may be a suitable complementary marker, at least until a more comprehensive COI reference database becomes available. DNA barcoding has successfully been used to identify amphibian larval stages (tadpoles) in species-rich tropical assemblages. Tissue sampling, DNA extraction, and amplification of COI is straightforward in amphibians and reptiles. Single primer pairs are likely to have a failure rate between 5 and 50% if taxa of a wide taxonomic range are targeted; in such cases the use of primer cocktails or subsequent hierarchical usage of different primer pairs is necessary. If the target group is taxonomically limited, many studies have followed a strategy of designing specific primers which then allow an easy and reliable amplification of all samples.